1. Technical Field
The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus.
2. Related Art
In recent years, efforts have been made to improve the speed and the reliability of image forming apparatuses of so-called xerography system, which has a charging unit, an exposure unit, a development unit, a transfer unit, and a fixing unit, through technical developments of the respective members and the system. Therefore, requirements for high-speed adaptability and high reliability of each subsystem are stronger than before. With respect to toners used in the image forming apparatuses, there have been attempts to, for example, reduce the particle diameter of the toner, decrease the particle diameter, make uniform the particle size distribution (reduce the particle size variation), and make the toner particles spherical. As a toner which meets such requirements in quality, a toner produced in a solvent composed mainly of water, or so-called chemical toner has been developed actively.
In particular, electrophotographic photoreceptors used for image writing are strongly required to have high-speed adaptability and high reliability. In order to achieve high-speed adaptability and high reliability, in particular, research and development regarding charge generating materials have been actively conducted. For example, a lot of reports have been made on the relationship between crystal forms and electrophotographic characteristics of phthalocyanine compounds, which are known as charge generating materials used in electrophotographic photoreceptors.
It is generally known that phthalocyanine compounds are classified into several crystal forms depending on their production method or treating method, and that the difference in crystal form significantly influences the photoelectric conversion characteristics of the phthalocyanine compounds. With respect to the crystal forms of nonmetal phthalocyanine crystals, crystal forms such as α, β, π, γ, and X forms are known.